Modular field device connection unit

Abstract

A field device connection unit has a main body, on which a plurality of connection elements for connection of connecting lines to field devices and a plurality of slots each intended for receiving a respective plug-in unit are arranged. The plug-in unit has a first group of field-side plug contact devices which are connected by the connection elements for connection of connecting lines to field devices, and a second group of system-side plug contact devices which are connected to a higher-level arrangement. For testing of the field device connection unit when the field wiring is disconnected, the plug-in units have a resilient latching cam, which latches switchably in a recess in the main body, the contacts of the second group of system-side plug contact devices being closed and the contacts of the first group of field-side plug contact devices being opened.

The invention claimed is: 
     
       1. A field device connection unit, comprising:
 a main body on which a plurality of connection elements is arranged for the connection of connecting lines to field devices; 
 a plurality of slots that are each configured to receive a plug-in unit, 
 wherein the plug-in unit includes: (i) a first group of field-side plug contact devices that are connected to the connection elements for the connection of connecting lines to field devices, (ii) a second group of system-side plug contact devices that are connected to a superordinated system, (iii) a switching mechanism including first and second switching positions, a resilient latching cam, 
 wherein the latching cam is configured to be retracted into the plug-in unit when it is in the first switching position and configured to project from the plug-in unit when it is in the second switching position, 
 wherein the main body includes a guide for each plug-in unit, the guide including a first recess configured to receive the latching cam, 
 wherein contacts of the second group of system-side plug contact devices are leading with respect to the contacts of the first group of field-side plug contact devices, and 
 wherein, when the latching cam is in its latched state in the first recess, the contacts of the second group of system-side plug contact devices are closed and the contacts of the first group of field-side plug contact devices are open. 
 
     
     
       2. The unit of  claim 1 , wherein the switching mechanism is configured as a slide whose direction of movement is oriented perpendicular to a plugging direction of the plug-in unit in a plane between the guides of the main body,
 wherein the latching cam is configured so as to be resilient in the direction of movement of the slide. 
 
     
     
       3. The unit of  claim 1 , wherein the switching mechanism includes a third switching position and a rigid locking cam which can be guided into a recess of the main body perpendicular to a direction of movement of the plug-in unit when the plug-in unit is completely inserted. 
     
     
       4. The unit of  claim 3 , wherein the guide of the main body includes a second recess that corresponds to the rigid locking cam when the plug-in unit is completely inserted. 
     
     
       5. The unit of  claim 1 , wherein the switching mechanism includes a center resting position in which the latching cam and the locking cam are configured to be retracted inside the plug-in unit.